Multiplier-quotient register state control means



H. GANG 2,620,979

MULTIPLIER-QUOTIENT REGISTER STATE CONTROL MEANS Dec. 9, 1952 4 Sheets-Sheet 1 Original Filed July 22. 1947 INVENTOR Dec. 9, H. GANG MULTIPLIER-QUOTIENT REGISTER STATE CONTROL MEANS Original Filed July 22. 1947 4 Sheets-Sheet 2 n l Y By '1 HERMAN GANG ATTORNEY H. GANG Dec. 9, 1952 4 Sheets-Sheet 3 Original Filed July 22. 1947 INVENTOR Z ATTORNEY Dec. 9, 1952 GANG 2,620,979

MULTIPLIER-QUOTIENT REGISTER STATE CONTROL MEANS Original Filed July 22, 1947 4 Sheets-Sheet 4 INVENTOR Patented Dec. 9, 1 952 UNITED STATES PATEN T O F' F l'CE :MULTIPLIER-QUOTIENT REGISTER STATE CONTROL MEANS HermanGang, Livingston, N. J assignor to Monroe Calculating "Machine Company, Orange, N.J.,-a corporation-of Delaware Continuation ofabandoned application Serial No. 762,614, July 22, 1947. This application March .7, 1951, Serial No. 214,420

for the multiplieruotient register 'toeifect like or unlike registrations respectively, .in arithmetical sign, the registrations effected ,in the product-dividend register.

Automatically operablemeansfor efiecting the desired settings of reversible drive means for a multiplier-quotient register is disclosed in Pat. #2260391 issued to Edwin F. BritteruJr. According to said disclosure, upon initial operation of reversible differential actuators -for a productdividend register, an independently reversible drive :means fora counter actuatorfor .a "multiplier-guotient register issetfrom a neutral ,position .into position to eifect .registrations 'alternatively like or unlike, 'in'ar'ithmetical sign, the registrations efi'ected in the product-dividend register. The reversible drive means of the counter actuator retains its setting at the end of a calculation and the automatic setting .means is effective only if the drive means is .in neutral position. Therefore, manually operable means is providedto restore the drivemeans .to neutral so that the proper setting will ,be assured upon initiation .of .a .following calculation. The .arrangement issuch that thedrivemeans will .be in an active position, or will be actively positioned upon initial operation of the .differentialactuators; therefore a count will invariablyberegistered in the multiplier-quotient register. This obviously necessitates acIearing operation for the multiplier-quotient register, when for example, a dividend is registered in the product-dividend register. The devices of the present invention eliminate the. necessity for the above noted clearingoperationfollowing a factor entering-operation and atthe same time render automatic settingmeans for reversible driv means ofa counter actuator effective for a following calculation in a machine wherein such setting means operates substantially in accordance with the aforenoted patent.

According to'thepresent invention, depression 2 of. a factor set-upkey is effective to causea singl cycle ofithedifferential actuators and thereby enter a value set on thekeyboard into the product-dividend register. Concurrently reversible drive means 'for the counter actuator, if in an effective position, is adjusted to neutral position. and'the setting means therefore is disabled during .the value entering operation. However, at the conclusion of the value entering operation'the setting means is reeenabled. If, when the setupkey is depressed, thedrive means has been. adjusted to neutral position, by other means "here- 'inafter described,.the disablin and re-enabling of the setting means will be effected. ,In either instance, no registration will be effected in the multiplier-quotient register during the factor entering operation, and the setting means willbe conditioned to properly adjust the driv means for ,the f ollowing .calculation.

The setting means for the reversible drive means .for thecounter actuator, with which the invention is .herein disclosed, operates substantially in accordance with the principles disclosed in th .afore .noted .Pat. #2360291. There is, howeyer, considerable deviation therefrom in .the structure .and the mechanical arrangement of .the parts. "Furthermore, the reversible drive for thecounteractuator, in lieuof the reversing geararrangement disclosed in said patent, comprises a pairof axially adjustable reversing cams whichoperate substantially in accordance with the principlesof Pat. #2,273,237 issued to Edward -C. Walter. The invention, however, will best'be understood from thefollowing description .of-apreferred embodiment with reference to the accompanyin drawings in which:

Fig.1 is a right side elevation of a calculating machine illustrating the control devices of the invention adjusted'to locate the'counter actuator in neutral position and the setting means :for the actuator rendered effective.

Eig. -'2 is -a fragmentary detail side view with parts broken away showing portions of the con- 'trol devices in position after the-setting means has adjustedthe counter actuator to an effective position.

Fig.3 isa fragmentary detail side view with parts broken away .showing other portions of the. control devices with the parts in theposition shownin ,Fig. 2.

Fig. 4 is adetail fragmentary plan view, showing the keyboard clearingand the tripping means ,for the .--machine stopping means with. parts broken away.

Fig. 5 is a detail plan view of the reversing cams of the counter actuator.

Fig. 6 is a vertical longitudinal section of the machine showing the keyboard, difierential actuators for the product-dividend register and the counter actuator for the multiplier-quotient register.

Fig. 7 is a left side elevation of the machine showing the actuator driving means and the stopping means therefor.

Registering mechanism (general operation) The product-dividend register I and the multiplier-quotient register 2 are mounted in a denominationally shiftable carriage 3 (Fig. 6). The actuating mechanism for the product-dividend register l comprises the differentially settable actuators 4 and the tens transfer actuators 5 which are mounted on and driven by transversely extending shafts t and '6 respectively in the body of the machine. The differential actuators 4 are settable by selection bails 8 in accordance with depressed keys 9 of the keyboard. The counter actuator for the multiplier-quotient register 2, designated generally by the reference numeral Ii), also mounted in the body of the machine, is driven by the transversely extending shaft ll.

Actuator shafts 6, 1 and II are driven by the motor I2 (Fig. 6) through the clutching and reversing differential drive l3 (Fig. '7). Differential drive 13 is constructed and operates substially in accordance with the disclosure of Pat. #1,566,650, issued to George C. Chase and is controlled by a compound clutch lever it which is fulcrumed on the machine frame. Upon rocking of clutch lever l4 from neutral in one or the reverse directions, the lever will engage and arrest rotation of clutch element IE or IE which will result in transmission of the drive in one or the reverse direction through gear IT to counter actuator shaft H. From shaft H, the drive is transmitted at a one to one ratio through gears i8, 59 (Fig. 1) to tens transfer actuator shaft 7 and to differential actuator shaft 6.

Drive means for the counter actuator It includes a drive control unit comprising independent reversing means which is adjustable into either of two direction controlling positions so that the counter actuator may be operated in the same or the reverse direction with respect to differential and tens transfer actuators 4 and 5 of the product-dividend register; or to a neutral intermediate position whereby the counter actuator is rendered ineffective to effect a count.

Actuator It comprises a series of countingfingers 23 (one of which is shown in Fig. 6) which are slidably mounted for vertical movement in a transversely and pivotally mounted frame 29. Fingers 23 are spring urged upwardly but are normally held in lowered position by a cam 21 fixed on shaft H and engaging a plate 30 having connection with a cross bar 32 which engages the bent over lower ends of said fingers. Upon rotation of shaft l l in either direction, cam 2'! will release and then redepress plate 30. Therefore, fingers 23 will be raised and lowered under control of cam 21. The reversing or direction controlling means for counting fingers 23 comprises a pair of integral and diametrically opposed cams 33 and 35 which are axially spaced and splined on shaft H to permit longitudinal adjustment. Thus, the cams may be adjusted as a unit to engage one or the other with a fork 35 which is fixed to frame 29, or to a neutral position thereby locating the cams upon opposite sides and out of active engagement with the fork.

As fingers 23 are raised under control of cam 27, one or the other of earns 33 or 3 3 if engaged with fork 35 will rock frame 29 and fingers 23 in one or the reverse direction and accordingly register a count in multiplier-quotient register 2. That is, the lowest order finger 23 when raised will engage a tooth space of an aligned numeral wheel gear and will effect a count of one in the related numeral wheel either like or unlike the registration being made simultaneously in product-dividend register I. The higher order fingers 23 operate to effect tens transfers and are restrained from operation, unless a tens transfer is indicated, by notched disks, one of which is secured to each numeral wheel of register 2. When cams 33, 34 are adjusted to neutral position at opposite sides of fork 35, fingers 23 will be raised and lowered upon operation of cam 2'! without the rocking motion and therefore no registration will be effected in the multiplier-quotient register.

Registering mechanism (plus and minus bar control) Clutch lever I4 is controlled by plus and minus bars 36, 37 substantially as disclosed in Pat. #2,096,465, to Austin A. Overbury to which reference is made for the operational details not disclosed herein. Depression of plus bar 36 or minus bar 37 (Fig. 1) will rock a shaft 38 clockwise or counter-clockwise respectively through linkage 39 and crank 46. Shaft 38 extends across the machine and has coupling connection 4| with a spring centralized setting plate 42 (Figs. 6 and 7) at the inner side of the left side frame. Plate 32, therefore, will be rocked counter-clockwise (Fig. '7) upon depression of plus bar 36 and clockwise upon depression of minus bar 31. Setting plate 42 is provided with a pair of opposed shoulders 62a adapted respectively for engagement with a pin [4a of clutch lever i i when the plate is rocked from central position. Therefore upon depression of plus bar 36 a shoulder 32a of plate 42 will rock clutch lever I4 clockwise (Fig. 7) to engage the transmission 93 for positive registration and upon depression of minus bar 31, the clutch lever will be rocked counter-clockwise to engage the transmission for negative registration.

FuZZ cycle stopping means Means settable upon depression of the plus bar 36 or minus bar 3? is operablaupon release of the depressed bar, to stop the registering mechanism in full cycle position at the end of the current registering cycle. When setting plate 42 is rocked to engage the drive, one or the other of a pair of opposed cam faces Will rock and hold a spring retracted lever 43 counter-clockwise (Fig. 7). A pawl 44 mounted on lever 43 is spring urged counter-clockwise but when lever 43 is in normal clockwise position a suitable stop pin (not shown) holds pawl id in the clockwise position shown in Fig. I. When lever 53 is moved counter-clockwise, pawl i will be moved away from the stop pin and a lug of the pawl will be rocked counter-clockwise into position beneath a lug of a tri ger 3|. Trigger ill normally engages a lug on a spring urged pawl 25 which is mounted on the upper end of a stop arm 24. A rock arm 22 has common pivotal mounting with arm 24 and is reciprocally driven in time with the actuating mechanism by a link 2! and a crank 28 which is fixed on tens transfer actuator shaft ll. Upon release of plus bar 36 or minus bar 3?, setting plate 42 will be centralized and lever 43 will be :raise the trigger and release pawl 25.

rocked clockwise to normal thereby engaging the lug of pawl 4a with the lug of trigger tlt rtlo As e parts approach full cycle position, a shoulder at the upper end of rock arm 22 will engage re- .leasedpawl 25 and arm 24 will be'oarried against astop '45 to arrest the movement of the-parts'in their over run beyond full cycle position. As arm .24 iscarried to stop 45, a cam slot of an extension Zliwofthe arm will engage a pin of clutch lever l4 thereby moving the lever to neutral position to disconnect the drive. Upon rebound of the parts from stop "45, the registering mechanism will be located in full cycle position by a locator cam (Fig. 1) ,"and'pawl 44 having been-moved to normal .in its tripping operation, will permit trigger 3i tore-"engage pawl 25.

Registering mechanism (non-repeat means) With plus or minus bar as, or held depressed, selectively operable means are provided to limit the registering mechanism to a single cycle of operation.

An upstanding trip arm ii (Figs. 1 and 3) has a'slot at its lower end whereby pivotal mounting is provided on a pin it and lateral adjustment of the lower end of the arm is permitted. A gear train comprising gears 49 (Fig. l), driven from the actuator drive gears, extends toward the front of the machine. A lost motion cam 50 (Figs. 1 and 3) is loosely mounted'on the shaft of the forwardmost gear 69 and a pin on the gear is adapted to engage and drive the cam. With the lower end of arm 4-? in the released position shown in Fig. 3, cam 50 operating in timed relation with the registering mechanism will be ineffective to rock said arm but will adjust its lower end toward the front of the machine. Thus the non-repeat means is disabled and the machine will cycle as long as a plus or minus bar is held depressed. When the lower end of arm A! is adjusted and held toward the rear (as hereinafter described) cam 50 will be effective, during the first cycle of the registering mechanism in either direction, to rock said arm and thereby trip the stopping means to terminate the registration upon completion of the single cycle as follows.

The upper end of trip arm 41 engages an arm of a bell crank 5| (Fig. 4;) and the other arm of the bell crank engages a slide 52 which extends across the machine and into engagement with an arm of a bell crank 53. The other arm of bell crank 53 engages the forward end of an intermediately pivoted lever 5 (Fig. '7) and the rearward end of the'lever has slot and pin connection with trigger 3|. Slide 52 has suitable lugs which engage latching bails 55 (Fig. 4) which hold depressed keys 9 of the keyboard against retraction. When trip arm 41 is rocked, bell crank 5i will be rocked thereby moving slide 52 to rock latching bails 55 to clear the keyboard; and also slide 52 will rock bell crank 53, lever 54 and trigger 3| to release pawl 25 and thereby operate the stopping means as heretofore described. Setting plate 62, however, must be centralized while a plus or minus bar is held depressed to permit clutch lever [A to be moved to neutral. For this end a pin on stop arm 24 will release coupling 4| thereby permitting the setting plate to be spring centralized and upon release of the depressed plus or minus bar the coupling will be moved into engaging relation with the setting plate.

The change lever (manual setting) The change lever 56 (Figs. 1, 2 and 3) may be manually set toward the front and toward the rear of the machine to adjust the heretofore described reversing cams 33, 34 of counter actuator I!) to effect the like and the unlike sign registrations respectively; or to the intermediate position whereby the counter actuator is rendered ineffective.

Change lever 58 is fulcrumed intermediate its ends on the right side frame. A link 58 has pivotal connnection to the lower of change lever 56 and extends to the rear of the machine where it has pivotal connection with an arm of a bell crank 65. The other arm of hell crank 60 has slot and pin connection with a slidably mounted forked plate 62 (Fig. 5) which engages the outer sides of reversing cams 33, 35. Upon counterclockwise movement of change lever 58 toward the front of the machine, as shown in Figs. 2 and 3, link 53 will be moved toward the rear thereby rocking bell crank (it) and moving forked plate 62 and cams 33, 34 toward the left of the machine to engage the rightmost cam 33 with the fork 35 of actuator 10, as shown in Fig. 5, to control like sign registration. Conversely, upon adjustment of change lever 55% toward the rear of the machine, the leftmost cam 35 will be moved to engage fork 35 to control unlike sign registration. Upon movement of change lever to its intermediate position, earns 33, 34 will be adjusted to positions at opposite sides of fork 35 and the counter actuator It will be disabled.

Change lever 53 is yieldably held in its adjusted positions by a locator arm 53 (Figs. 1 and 2) which has common pivotal mounting with link 58 on the change lever and which is spring urged counter-clockwise. Change lever 56 is held in its intermediate position (Fig. 1) by engagement of a notch 65 in the upper edge of arm 63 with the wedge shaped end of a stub shaft (56 on which a gear 6! is rotatably mounted. Arm 63 is recessed at 68 on either side of notch 65 and when the change lever is moved to either of its active positions (Fig. 2), arm E3 is spring raised to engage either one or the other of recesses 68 with shaft 66.

Means operating in conjunction with a keyboard clearing operation is provided to adjust change lever 55 to its intermediate positionpso that the automatic setting means (to be 'described) will be rendered effective.

A pin 6.9a on the stem of a clear key is (Fi l) overlies an arm it fixed to a bail H (Fig. 6) which overlies the forwardly bent ends of the stems of the zero keys. The keyboard is of well known construction wherein the depression of any key operates to release any set key in the related column. Therefore, upon depression of clear key 69, pin 69a will rock bail H and depress all of the zero keys and thereby clear the keyboard.

Another pin 8922, mounted on the stem of clear key 69, has slotted connection with scissor plates '12. The scissor plates have common pivotal mounting with change lever 53, and upon depression of clear key 69, pin sec will move the active edges of the scissor plates towarda common center. A lug 58a carried by the change lever is positioned between the edges of the scissor plates and as these edges are moved toward each other, upon depression of clear key one or the other of the edges will engage lug 56a and move change lever 55 to its intermediate position. Lug 58a is mounted upon a slidable portion of change lever 56 so that the lug may be raised above the-scissor plates to render the plates ineffective upon the actuators and effective only when the lever is in its intermediate position. The setting means includes the gear (Figs. 1 and 2) ro- 'tatably mounted on stub shaft 65 and driven through the gear train 49 at a one-to-one ratio with the register actuating mechanism. Gear 6! is provided with a segmental flange 13, the ends of which lie, when the parts are in full cycle position and change lever 55 is in its intermediate position, at either side of a pin 63a mounted on and extending inwardly of locator arm 63.

Upon initial rotation of the actuators in either direction, one or the other end of flange '13 will engage pin 63a thereby unseating locator arm 63 from its intermediate position and urging it in one or the other direction where it will be raised and located by registration of one or the other of its recesses 68 with shaft 66 as shown in Fig. 2. Accordingly, change lever 55, having connection with arm 63, will be rocked to one or the other of its active positions. Upon further rotation of gear 61 and flange 13 as the registering mechanism is operated, the change lever will remain adjusted in active position as pin 65a raised with arm 63 will have been moved inwardly between the ends of the flange and out of the path of movement thereof as shown in Fig. Positive registration, as in a program of multiplication, will result in counter-clockwise rotation of gear 61 and flange l3 thereby setting the change lever counter-clockwise so that like sign registration will be effected in the multiplierquotient register. Conversely minus registration, as effected in the initial operation of a division program, will result in clockwise rotation of gear 61 and flange i3 and the change lever will be set to control unlike sign registration.

Factor entering means and disablement of counter actuator The devices of the invention provide means whereby a single cycle of the registering mechanism is efiected to enter a value set on the keyboard into product-dividend register as a factor such as a dividend. The means whereby the factor entering operation is initiated restores change lever 56, if in one of its active positions, to its intermediate position. The setting means, however, for the change lever is disabled during the single registering cycle and then re-enabled at the termination of the cycle. Thus no count will be registered in the multiplier-quotient register and the setting means will be rendered operable to effect the proper setting of the change lever for the following calculation.

The devices comprise a spring retracted setup key I4 (Figs. 1 and 3) having an arm Ma overlying a pin 36a on the stem of plus bar 36. Pivotally mounted at its upper end on the stem of key M is an arm 15, the lower free end of which overlies a pin 160, on a crank 16 which is pivotally mounted to the machine side frame. Arm 15 is spring urged clockwise into engagement with a lug on a latch arm 11. Latch arm 17 is pivotally mounted at its upper end to the machine side frame and is spring urged clockwise into engagement, adjacent its lower shouldered latch end, with pin 16a of crank 16. The upper edge of link 58 is provided with a pair of oppositely disposed cam faces 18 extending from opposite sides respectively of a centering recess 19. The pin 16a of crank 15 extends outwardly above link 58 and into a slot 64 of locator arm 63.

Upon depression of set-up key 14, the free end of arm 15 will engage and depress pin 16a thereby rocking crank 16. If change lever 56 is in one of its active positions (Figs. 2 and 3), pin 16a, upon depression, will engage one or the other of cam edges 18 of link 58 and move said link and the connected locator arm 63 and change lever 56 to their intermediate position at which time pin 16a will have entered centering recess 19. Furthermore in its downward movement, pin 16a will displace locator arm 63 clockwise and its pin 63a will be moved to the outside and out of the path of movement of flange 13 thereby disabling the change lever setting means. As the parts are moved into position, as above described, arm 14a of the seteup key 14 will depress the plus bar and positive operation of the registering mechanism will be initiated. As change lever 56 is moved to its intermediate position, the non-repeat means is rendered effective. Such means comprises an arm 56a of the change lever; and as the lever is moved to its intermediate position the arm will be moved into blocking engagement with a roller at the lower end of trip arm 41. Cam will'now be effective to rock trip arm 4'! so that the registration will be limited to a single cycle and the keyboard cleared. As pin 16a completes its downward movement, the shouldered free end of latch arm 11 will be moved into latching position above said pin. Therefore pin 16a and the connected parts will be held in fully depressed position should set-up key I4 be released during the set-up cycle.

Upon the overrun of the registering means in the stopping operation, a cam 80 (Fig. 3) will rock latch arm 71 and arm 15 counter-clockwise to release pin 76a and the parts connected therewith. Cam 8%) is loosely mounted on shaft 66 and has a lug 80a which, when the registering means makes the overrun, is engaged by one or the other side of a cut away hub 61a carried by gear 87. Upon release of the parts by latch I 1, locator arm 63 will be moved counter-clockwise. At this time, arm 63 will not be afforded its full movement as the registering mechanism will be in its overrun beyond full cycle position and pin 63a will engage the outer side of flange 13. However, when the registering means rebounds to full cycle position, pin 530. will be allowed .passage between the ends of flange l3 and locator arm as will be moved counter-clockwise to seat its notch on shaft 66. Obviously if change lever 56 is in its intermediate position when setup key M is depressed, pin 16a of crank 16 will be allowed direct entrance into recess (9 of link 58 and the resulting operations will all be effected identically as described in the foregoing.

The foregoing description relates to the setting up of a dividend. However, a cycle of differential actuators of a calculating machine has been used in the art to enter a multiplier in a series of storage devices, as for example, in applicants Pat. 412,531,266. Obviously, therefore, it is within the scope of the present invention to control registration in a multiplier-quotient register as an incident to a multiplier set-up operation. The broad concept of the invention contemplates means for disabling the counter actuator during a factor entering operation in conjunction with automatic means conditioned to re-enable the actuator at the end of the factor entering operation. Although the devices of the invention have been disclosed in conjunction with means which enable and at the same time control reversibility of the actuator, it will be apparent that the invention would be equally usable with means effecting only the disabling and enabling functions in which instance one of the principal objects of the invention would be achieved i. e. the elimination of a count in the multiplier-quotient register. It will be understood, therefore, that although one of the principal uses of the invention is its application in connection with change lever control, the invention is not necessarily restricted thereto.

I claim:

1. In a motor driven calculating machine having a product-dividend register, a multiplierquotient register, motor driven actuating means including differential actuators for said productdividend register and a counter actuator for said multiplier-quotient register, and a drive control unit adjustable into position to enable or alternatively into position to disable said counter actuator; the combination of a power train driven in timed relation with said actuating means and operable upon initial movement thereof to adjust said drive control unit from disabling to enabling position, a member between said power train and said drive control unit displaceable to render said train ineiiective, an operating key, adjusting means operable upon depression of said key to displace said member, means operable upon depression of said key to initiate operating of said actuating means, and means operable to restore said member.

2. In a motor driven calculating machine having a product-dividend register, a multiplierquotient register, motor driven actuating means including differential actuators for said productdividend register and a counter actuator for said multiplier-quotient register, and a drive control unit adjustable into position to enable or alternatively into position to disable said counter actuator; the combination of a power train driven in timed relation with said actuating means and operable upon initial movement thereof to adjust said drive control unit from disabling to enabling position, a member between said power train and said drive control unit displaceable to render said train inefiective, an operating key, adjusting means operable upon depression of said key to adjust said drive control unit to disabling position and to displace said member, means operable upon depression of said key to initiate operation of said actuating means and means operable to restore said member.

3. In a motor driven calculating machine having a product-dividend register, a multiplierquotient register, reversible motor driven actuating means including differential actuators for said product-dividend register and a counter actuator for said multiplier-quotient register, and an independent reversal control unit adjustable from a neutral position, wherein said counter actuator is disabled, into one or alternatively another eiiective position wherein said counter actuator is operable in like or unlike direction respectively with relation to said differential actuators; the combination of a power train driven in timed relation with said actuating means and operable to adjust said reversal oontrol unit into one or alternatively its other effective position in dependence upon the direction of the initial registering movement of said differential actuators, a member between said power train and said reversal control unit displaceable to render said train ineffective, an operating key, adjusting means operable upon depression of said key to displace said member, means operable upon depression of said key to initiate operation of said actuating means, and means operable to restore said member.

4. The invention according to claim 3 wherein the adjusting means is operable upon depression of the operating key to adjust the reversal control unit to neutral position.

5. The invention according to claim 3 wherein the means operable to restore said member is responsive to the operation of the actuating means.

6. In a motor driven calculating machine having a product-divider register, a multiplierquotient register, reversible motor driven actuating means including differential actuators for said product-dividend register and a counter actutor for said multiplier-quotient register, and an independent reversal control unit adjustable from a neutral position, wherein said counter actuator is disabled, into one or alternatively an other effective position wherein said counter actuator is operable in like or unlike direction respectively with relation to said differential actuators; the combination of a power train driven in timed relation with said actuating means and operable to adjust said reversal control unit into one or alternatively its other effective position in dependence upon the direction of the initial registering movement of said differential actuators, a spring retracted member between said power train and said reversal control unit displaceable to render said train ineffective, an operating key, adjusting means operable upon depression of said key to displace said member, a latch operable to hold said member displaced, m ans operable upon depression of said key to initiate operation of said actuating means, and means responsive to the operation of said actuating means for releasing said latch.

The invention according to claim 6 characterized by the provision of means for adjusting the reversal control unit to neutral position upon depression of the operating key comprising said adjusting means.

8. In a motor driven calculating machine having a product-dividend register, a multiplierquotient register, cyclic reversible motor driven actuating means including differential actuators for said product-dividend register and a counter actuator for said multiplier-quoti nt register, full cycle stopping means for said actuating means, and an independent reversal control unit adjustable from a neutral position, wherein said counter actuator is disabled, into one or alternatively another effective position wherein said counter actuator is operable in like or unlike direction respectively with relation to said differential actuators; the combination of a power train driven in timed relation with said actuating means and operable to adjust said reversal control unit into one or alternatively its other eiiective position in independence upon the direction of the initial registering movement of said difierential actuators, a member between said power train and said reversal control displaceable to render said train inefiective, non-repeat means operable to initiate operation of said stopping means upon a single cycle of operation of said actuating REFERENCES CITED The following references are of record in the file of this patent:

Number 12 UNITED STATES PATENTS Name Date Schaller Dec. 13, 1921 Chase Aug. 12, 1924 Chase Mar. 17, 1936 Hilder May 30, 1939 Kottmann Jan. 7, 1941 Britten Oct. 28., 1941 Britten Jan. 20, 1942 Walter Feb. 17, 1942 Machado Jan. 2, 1945 Boyden Jan. 15, 1946 

